[K12OSN] OT: Build a server challange :-)

[Jim Kronebusch]

> You have to solve your speed problem with the nfs-mounted /home first. 
> Can you repeat your tests using a standalone server first, then 
> nfs-mounting a /home directory (using a separate interface for the mount 
> if possible), and then adding the LDAP authentication so you can see 
> where the slowdown happens and try some options to fix it?  Be sure the 
> nfs mount is async and has a reasonable block size specified. There 
> shouldn't be that much difference when reading over nfs.

I have to say I really wanted to run a massive /home server and a separate LDAP then
have all servers talk on a separate gigabit backbone LAN.  But the speed thing stopped
me.  When I did my testing this was all on a Gig LAN and non-production servers.  I
first had my standalone server, then added LDAP and /home at the same time.  When I saw
the speed issues I dropped /home and just used LDAP.  The speed problem was cut in about
half.  Then I added /home back on and dropped LDAP for local accounts, speed stayed
about the same.  So it seemed that each service contributed to about half of my couple
second lag compared to standalone.  Right now I have the same server serving a small
test lab of 15 clients with /home NFS mounted from my current file server but using
local unix accounts.  I just want to get rid of that 1-2 second lag that I didn't have
when everything was local.

As far as async goes, I had just used the default /home export config from a k12ltsp
server.  Here is the export line in my current file server:

/home   10.6.0.0/255.255.0.0(rw,no_root_squash,sync)

Now I know that exporting to the entire 10.6.x.x network isn't exactly secure, but I
don't really care at this point.  However I see that the export uses sync instead of
async.  I also see that the /var/opt/ltsp/swapfiles are exported with async and
/opt/ltsp/i386 is exported with sync.  What is the difference?  If exporting with async
is faster why isn't k12ltsp set this way by default?

I will try and change my export to async and see if it makes a difference.  If it does I
will try adding LDAP back to it and see if my speed issues go away.

> I'd also try to build a backup system.  Backuppc running on a fast 
> desktop box with a big disk in another room might be good enough but 
> anything that you can't replace should have offsite copies.

I have a 1.5 TB dedicated backup server right now that backs up all servers over the
network.  I am using Retrospect server for backups at this point, but always remember
Backuppc for when it is time to upgrade.

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